and positron can bind into an atom-like structure called positronium. Describe positronium using the Bohr model. Assume that the electron and positron each travel in a circle about a point halfway between them.

Consider the motion of the electron. Find a relation between R and v that must be satisfied if the electron's orbit is to be a circle.

Would you change Bohr's quantum condition or keep it the same as in hydrogen? State what condition you would use and why you would choose it.

What is the energy gap between the ground and first excited state of positronium in your model? How does it compare to the analogous gap in hydrogen?